Conduction velocity distribution of afferent fibers in the female rat hypogastric nerve.

Conduction velocities of single afferent fibers in the female rat hypogastric nerve were measured by stimulating dorsal rootlets and recording from the hypogastric nerve. A total of 344 units were identified and measured. They were distributed among dorsal roots T13 to L3 ipsilaterally (75%) and between L1 and L2 contralaterally (25%). Over 95% were found in the L1 plus L2 dorsal roots. Ninety-six percent of the units had conduction velocities less than 2 m/s; the average conduction velocity was 0.98 m/s. By way of contrast, afferents in the postganglionic nerves innervating the urinary bladder with conduction velocities less than 2 m/s constituted 65% of the afferents. We conclude that the overwhelming majority of afferents in the female rat hypogastric nerve are unmyelinated C-fibers.